Alexandra Matei


THE PRESENTATION OF SILKMOTH BOMBYX MORI L. SP. GENETIC RESOURCES IN ROMANIA AS SOURCE OF INITIAL MATERIAL IN AMELIORATION WORKS

Alexandra Matei, G. Chioveanu, M. Androne, D. Dezmirean, M. Dolis, I. Pasca, M. Bentea

Abstract
The importance of gene bank existence as an essential condition for amelioration programs elaboration is unanimously known for every plant and animal species, from which the permanent preoccupation for its diversification and maintaining by appropriate proceedings of preservation “in situ” or “ex situ”. This way, there is being avoided the loss of biological material, especially of the local races resistant to diseases and adapted to environmental conditions. This study aims the analysis of phenotypic characters variability within the genetic stock of Bombyx mori sp., according to its biological development stages (egg, larva and pupa). Native genetic stock of silkmoth Bombyx mori L. sp. resulted by: identification of local populations gene sources, bilateral exchange of biological material with similar foreign institutes, creation of new genotypes using specific breeding methods. Within its structure, the genetical stock of silkmoth include 72 races. The silkworm specific experimental technique has been applied, differentiated by technological and biological development stages. The sample size that were the base for phenotypic parameters determination as well as the working methods correspond to sericulture technical standards. The main phenotypical and quantitative parameters of the races that represent the gene stock of Bombyx mori sp., have the following values: prolificacy (230-710 eggs/laying), hatchability (80.6-100%), larval stage duration (26-32 days), larvae weight (4.2-5.7 g), larvae pupation rate (80.8-96.6%), raw cocoon weight (1.445-2.361 g), cocoon shell weight (0.240-0.520 g), fiber length (746-1356 m), filament size (2917-3764 m/g). Depending on the quantitative parameters value, the silkworm races are being used differently, entire genetic stock being destined for various technological levels, as follows: 4 active races (parents of hybrids), 3 candidate races for parents of hybrids, 65 races in preservation.

Key words: Bombyx mori, genetic stock, raw cocoon weight, cocoon shell weight, fiber length